CENTER-OF-MASS STAND

Load Board Angle Board

2x4

2x10

2x10

56"

2x4

2x10

All 2x4

2x4

9.5"

66"

NOTES:

The stand is NOT designed for DYNAMIC LOADS. Use STATIC LOADS ONLY! That is, when applying a load to the Load Board, do so slowly and gently!

The stand comes in two pieces: the Angle Board and the Load Board. The load board is removable. It slides in between the two 2x10s on the Angle Board. When we've used it as a demo we sometimes have a vertical support under the end of the Load Board and pretend to the audience that we've just constructed and interesting object. Then we (carefully) take out the vertical piece. The reaction is usually pretty good.

The 2x4s and the 2x10s attached to the Angle Board were fastened using 3" sheet-rock screws. This may not be the best way. The 2x4s are what taking the load from the Load Board. The 2x10s are used to distribute the load from the Load Board to the 2x4s.

The 2x10 at the bottom of the stand is used to add stability and carries no load.

The cross pieces in the Load Board are used for stability and carry no load.

One can place a light board on the Load Board to use as a seat.

The location of the load can be adjusted several ways. One can add weights to the Load Board or Angle Board. One can build different lengths of the Load Board or Angle Board. People of different weights will have to sit at different locations.

The angle board is cut so that the Angle Board is at 45⁰ to the floor. There's nothing magical about this angle.

Recommendations: If I were to build it again I would make the mass off the Angle Board greater. (One can just add weights, too.) I would also find a better way to attach the 2x10s and 2x4s to the Angle Board. There can be a lot of creaking when a load is applied.

TO USE:

Have two people assist. One person holds the Angle Board at the top end and another person holds the end of the Load Board. The third person slowly and gently sits on the Load Board. The two assistants can tell when the stand is balanced and should advise the person sitting on the Load Board on how to position themselves.

John Reid

Geology & Physics Dept

Lock Haven University

Lock Haven, PA

(570) 893-2078

jreid@lhup.edu